Double purpose weapons.
Mine Torpedoes have flat round heads and cylinder shaped bodies, they often have flaps at the bottoms and the bottom have of their bodies are thrusters.
The dome of one of these devices is a cluster of sensors to pick up on nearby enemies. They usually have whitelist style parameters for who not to target. Should the enemy get past them, they will rise up out of the ground to fly after them.
Their payload varies, but they are usually typical detonators.